I'm sure DB has an automated email list system. I can speculate that every customer has had an email along the lines of:
"Dear Precious Boutique Friend,
Certain malicious grovellers have posted reviews on TripAdvisor which have failed to grasp the quality of guests who grace our modest hotel.
It would make the staff and me immensely happy if you, your relatives, children, grandchildren, friends and colleagues, would post a favourable review correcting the false accusation that we are unfriendly to those unfortunates not sufficiently successful in society to stay at our oasis of excellence in the desert of mediocrity that surrounds us and merely wish to explore the magnificent menu which you, our wonderful life-achieving residents, enjoy on a daily basis.
Looking forward to buying you a drink in the bar next year.
Your loving and ever-attentive friend
Kostas"